Tuning the RS3! Episode 2 Cracking the ECU.

If you saw my first blog on the RS3 you’ll know that the car is really pretty awesome out of the box. I did have a few quips with the motor though. The torque curve has an odd dip in the mid range and torque is noticeably restrained. The car really rips up top even in stock form, but the mid range leaves you wanting more. It has less torque stock then a modified Golf R or Audi S3, which is what many buyers are coming from. Obviously, this had to be rectified.

Breaking in to the RS3 ECU

Our first task was to break into the Bosch ECU that controls the engine. Our software engineers worked tirelessly, picking through the factory binary and unlocking its secrets in order to gain access. With the factory security “fingerprint” technology, just being able to write in a single tiny change is the first major hurdle, let alone actually finding the tuning and figuring out how to get power out of it. This process took a few weeks to truly break into the ECU and give us free reign. If you don’t get this right, the ECU just won’t talk to you anymore and won’t run the car after you write in even one single change!

Tuning the RS3 for Power

It was clear right out of the box that the car has plenty of turbocharger flow available, just waiting to be turned up. However, the engine is actually pushing fairly hard at the higher rev band stock. Several hardware components, including the intercooler and the restrictive factory downpipe really hold it back and drive down how much power you can extract on pump fuels. I worked both on the dyno and off, daily driving the car for nearly a month and data logging constantly to balance these conflicting demands and extract more safe power. Managing the factory intercooler to maintain a reasonable intake air temperature is a huge factor!

Getting the RS3 right under ALL conditions

We put the car on our Dyna-Pak chassis dyno for further development, and hooked it up to our air pressure test stand. This 60 horsepower behemoth of a fan allows us to test the engine at altitudes between -500 feet and 6000 feet without even leaving our building. The calibration and especially boost control and fuel flows were initially checked using this setup. Huge gains were found especially in mid range torque. It’s looking like final numbers will be in excess of a 85 wheel torque gain in the mid range!

The Nitty Gritty...

Tuning doesn’t just stop there at mapping the ecu for more power though. I also addressed issues with boost control, giving the ECU tighter control over how much boost is being delivered to the engine. In factory form it actually overshoots target quite a bit and is quite sloppy with the boost control. Launch control was reworked, resulting especially in significant gains in the 0 to 60. The factory launch control will build quite a bit of boost if you request it, plenty to completely annihilate the snow tires we have on the car right now. Most likely we’ll make several different launch boost pressures available so customers can match the launch up to the tires they have on the car.

Here’s the car backed up to a set of gnarly tracks it laid down when I dialed in too much launch boost pressure haha. It didn’t go any faster like this just took a few thousand miles off this set of snow tires.

I was able to obtain a .4 second decrease in 0-60 times, from 4.1 to 3.7, despite having swapped the car from the summer tires to a set of greasy Blizzack snow tires. I expect that to improve when it gets some real tires on the car next spring. The 0-100 time has fallen down a full .8 seconds already as well, down from the 10.0 seconds we measured stock.

Finally, in the interest of reworking the entire driving experience, I reworked tuning for the exhaust flaps so that under heavy acceleration they open in all modes at all RPM’s, instead of only at high RPM. This actually gives a nice gain in spool time, netting around 200 rpm faster spool and reducing knock in those lower RPM. As an enthusiast too, I just found the car way too quiet under acceleration in modes like manual, where the flaps wouldn’t open until you really rev it out.

While many tuners give up to temptation to just throw parts on the car to solve it’s issues, I really wanted our basic stage 1 calibration to be absolutely perfect, and extract the most out of the stock hardware as it comes out of the box. With that in mind, once the RS3 was running really damn well here, we planned a trip to California to get in some sea level, warm weather testing prior to release of this software. More on that next time!

Thanks for sharing this valuable information. ECU is not a jumble of belts and wires at all. This particular part of the car has a high level of sophistication, and makes use of microprocessors and sensor data that can be processed to perform in real time. As a part of modern technical advance, the ECU is not something that is ordinarily fine-tuned with a monkey wrench or pair of pliers. All part of an engine management system that will allow for a much better fuel economy and a more responsive performance. It also means there is a smaller amount of emission coming from the vehicle, which is great for the environment.

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